Drought conditions worsen in Georgia

David Emory Stooksbury, University of Georgia | Aug 31, 2007

Drought conditions across Georgia have worsened dramatically since the beginning of August. Widespread triple-digit high temperatures and very little rain have caused soil moisture levels to plummet, stream flows to approach record lows and groundwater and lake levels to drop sharply.

The only exception to the state's dramatically worsening drought is in the interior southeast, where 30-day rainfall amounts have been 130-200 percent of normal.

In late August, of Georgia's 159 counties, drought conditions were classified as exceptional in 70, extreme in 40, severe in 15, moderate in 13 and mild in six, with 11 counties classified as abnormally dry. Four counties are classified as not being in drought.

In early August, drought conditions were exceptional in 37 counties, extreme in 55, severe in 16, moderate in 21 and mild in 10, with eight abnormally dry. Twelve counties were classified as not being in drought.

In late June, no counties were in exceptional drought, but conditions were extreme in 104 and severe in 38. Then, conditions were moderate in just 15 and mild in only two, and no county was just abnormally dry or not in drought.

Drought conditions are expected to be "exceptional" about once in 100 years, "extreme" once in 50 years and "severe" once in 20 years. The classifications are based on many indicators, including rainfall since Oct. 1 and over the past 180, 90, 30 and 14 days, soil moisture, stream flows, groundwater levels and reservoir levels.

Counties in exceptional drought are in southwest and north Georgia. The 19 southwestern counties are west of a line through, and including, Thomas, Colquitt, Mitchell, Dougherty, Lee, Terrell, Webster, Marion and Stewart.

In north Georgia, the 51 counties classified as in exceptional drought are north of a line through, and including, Troup, Meriwether, Pike, Spalding, Henry, Newton, Walton, Oconee, Clarke, Madison and Franklin.

Extreme drought conditions are in west-central and south-central Georgia and the south central and southeastern piedmont. In west central Georgia, Bibb, Chattahoochee, Crawford, Harris, Lamar, Marion, Monroe, Muscogee, Peach, Schley, Talbot, Taylor and Upson counties are classified as in extreme drought.

The four counties not classified as in drought — Laurens, Montgomery, Treutlen and Wheeler — got beneficial rains from the remnants of tropical storm Barry and continue to get timely and bountiful rains.

However, even the counties where the drought is now mild or better could see conditions deteriorate quickly if temperatures remain high and timely rains fail to materialize.

High temperatures combined with little rainfall will result in the soil drying quickly and plants becoming stressed.

Soil moisture is near the 1st percentile across most of west and north Georgia. At this level, we would expect the soil to be moister in 99 of 100 years.

Most streams across west and north Georgia are at or near record low flows for late August. The Chattooga River in the northeast mountains is approaching an all-time record low flow. The stream gauge data for the Chattooga goes back 67 years.

In southwest Georgia, Spring Creek near Iron City has stopped flowing.

Soil moisture loss to evaporation and plant use is now running between one-quarter and one-third of an inch per day.

Groundwater levels remain low statewide for this time of the year.

No widespread relief is foreseeable. In August and September, the best hope for widespread drought relief is from tropical weather systems. Without these, we can expect the drought to worsen over the next two months.

If dry conditions continue, high temperatures above normal are expected to continue.

Get updated drought information at http://www.georgiadrought.org. The state drought Web site includes information on how to deal with the drought.

EDITOR’S NOTE — David Emory Stooksbury is the state climatologist and a professor of engineering and atmospheric sciences in the University of Georgia College of Agricultural and Environmental Sciences.